Traditionally, phase shifters are used in radio frequency (RF) discrete systems, where various high quality components are combined to achieve the required performance. These components are generally made of various materials and substrates. In order for the performance of these components to meet the system requirements, the quality factor for those components is usually high. As technology develops, most of the RF discrete components have become integrated in an integrated circuit (IC) process where lossy substrates are unavoidable due to cost and compatibility. Therefore, an analog phase shifter implemented as an IC must deal with an effect of a low quality factor for components that comprise the phase shifter.
Many prior art techniques that generate continuous phase shift (see, e.g., U.S. Pat. No. 5,028,892 and U.S. Pat. No. 5,119,050) have relied on circuits comprising high quality factor components (transmission line, gallium arsenide (GaAs) components, silicon-on-insulator (SOI) components, etc.). Some prior art techniques described the generation of continuous phase shift in an IC process (U.S. Pat. No. 7,333,790); however, these techniques cannot deliver the performance in terms of low insertion loss and good phase linearity, which can be achieved by others that utilize high quality factor components made of various materials and substrates.
Accordingly, there is an opportunity for systems and methods for a continuous, linear, 360-degree analog phase shifter, which may achieve stringent performance requirements and likewise be integrated into a low-cost IC process such as a complementary metal oxide semiconductor (CMOS) process.